SOLUTION: Solve the system of equations by the addition method..All I have. x-4y=-18 -6x+4y=-36

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Question 34727This question is from textbook Prealgebra & Introductory Algebra
: Solve the system of equations by the addition method..All I have.



x-4y=-18
-6x+4y=-36
This question is from textbook Prealgebra & Introductory Algebra

Found 2 solutions by hydromojo, ichudov:
Answer by hydromojo(20) About Me  (Show Source):
You can put this solution on YOUR website!
Just add the 2 equations, that way you get rid of the 'y' term
you get +-5x+=+-54+
so, x = 10.8
use this value of x in either equation, say in eqn#1, so
+10.8+-+4y+=+-18+
so, -4y = -28.8 and y = 7.2

Answer by ichudov(499) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Linear System solver (using determinant)
Solve:
+system%28+%0D%0A++++1%5Cx+%2B+-4%5Cy+=+-18%2C%0D%0A++++-6%5Cx+%2B+4%5Cy+=+-36+%29%0D%0A++

Any system of equations:
+system%28+%0D%0A++++a%5B11%5D%2Ax+%2B+a%5B12%5D%2Ay+=+b%5B1%5D%2C%0D%0A++++a%5B21%5D%2Ax+%2B+a%5B22%5D%2Ay+=+b%5B2%5D%29%0D%0A++

has solution
+system%28+%0D%0A++++x+=+%28b%5B1%5D%2Aa%5B22%5D+-+b%5B2%5D%2Aa%5B12%5D%29%2F%28a%5B11%5D%2Aa%5B22%5D-a%5B21%5D%2Aa%5B12%5D%29%2C%0D%0A++++y+=+%28a%5B11%5D%2Ab%5B2%5D+-+a%5B21%5D%2Ab%5B1%5D%29%2F%28a%5B11%5D%2Aa%5B22%5D-a%5B21%5D%2Aa%5B12%5D%29%0D%0A++++%29%0D%0A++
or

+system%28+%0D%0A++++++x+=+%28-18%2A4+-+-36%2A-4%29%2F%281%2A4--6%2A-4%29+=+10.8%2C%0D%0A++++++y+=+%281%2A-36+-+-6%2A-18%29%2F%281%2A4--6%2A-4%29+=+7.2%0D%0A++++%29%0D%0A++

(x=10.8, y=7.2}